SNP MP Ian Blackford warned the British Government his party is prepared to hold a second independence referendum should Theresa May fail to safeguard the Scottish economy with her brexit strategy.

The SNP's Westminster leader issued the stern warning to force the British Government into reconsidering its decision to leave the single market and the customs union as part of its Brexit strategy.

Nicola Sturgeon's party has long lamented that leaving the European Union would have dire effects on the Scottish economy and demanded Prime Minister Theresa May reconsiders her position.

During an appearance on BBC show Any Questions?, Mr Blackford said: "Something very important happened in Parliament just last week because we had a debate on the claim of right and the issue of where sovereignty rests and Parliament accepted that, unlike in the English system where sovereignty rests with Parliament, in Scotland sovereignty rests with the people.

"Westminster better realise that there is a mandate that the Scottish Parliament has and if the Scottish people chose to have that vote on their future at the right time, we’ll be having it."

Mr Blackford also said the SNP would work with the British Government over the last few months of the Brexit negotiations with Brussels to safeguard the interests of Scotland.

He insisted membership of the single market and the customs union were not part of the 2016 EU referendum and suggested a majority of MPs was of the same mind with the SNP.

The Scottish politician continued: "What I would say is, we will take our responsibilities over the coming months to do all we can to work across party and to encourage other members of parliament to get to a position where we stay in the single market and the customs union.

"That’s the first priority. I firmly believe that there is a majority in the House of Commons for that and I would simply make the point that membership of the single market and the customs union was not on the ballot paper.

"Scotland is dragged out of the single market and the customs union against its will then we have to remember that the SNP won a mandate to put the independence question to the people’s of Scotland if there’s a material change of circumstances."

If the Scottish people chose to have that vote on their future at the right time we’ll be having it

Ian Blackford

First Minister Sturgeon in May argued that a new Scottish independence referendum was "much bigger case than Brexit."

She also claimed that some aspects of the Brexit debate had added fuel and strengthened her plans to see Scotland break away from the UK.

The SNP threat comes as Mrs May fights off pressure from Brexit hardliners in her party voicing concerns over the Government's latest Brexit blueprint.

Her proposal would see Britain maintain its close trading links with Brussels through a free trade area administered by a common rulebook.

But Brexiteers fear the common rulebook would leave the country under EU rule without any say on regulations after British politicians lose their institutional seats after withdrawal.

Sir Bill Cash slated the White Paper proposal, expressing concerns the UK would become a vassal state and be forced to accept regulations in the same manner as the 1972 European Communities Act.

Former cabinet minister, Thersa Villiers, also criticised the White Paper, and said: "The Chequers agreement indicated that Parliament will have the right to reject future EU rules, but how will they ever exercise that power when the White Paper commits to an upfront choice to commit by treaty to ongoing harmonisation of the relevant EU rules?"

The 98-page blueprint set out details for the UK's future relationship with the EU when it was finally published earlier today.

The white paper was expected to be published last month but was delayed after constant disagreement between cabinet ministers.

The document detailed the government's plans for the future economic and security partnership with the EU, as well as other cooperative and institutional arrangements once Britain leaves the bloc.